Summary: One of the major goals of the USPHS is the regional elimination of measles by the year 2000, a goal that is achievable due to an increase in immunization rates and implementation of a two dose schedule for measles vaccine. However, there are still some unanswered questions regarding optimal use of measles vaccines . For example, research is needed in order to understand the safest method for immunization of immunocompomised children, such as those with HIV infection, who could suffer serious disease as the result of measles infection or serve as a focus of persistent shedding and spread of measles virus that could impede eradication efforts. In addition, increasing numbers of infants are born to mothers with vaccine induced immunity. These mothers have lower levels of measles antibody than mothers with immunity induced by wild type measles infection. As a result, infants born to vaccinated mothers have lower levels of passively acquired antibody at birth and these infants become susceptible to measles infection early, with loss of antibody by 6-9 months of age. Previously, vaccine failure in infants less than 12 months of age was thought to result from neutralization of vaccine virus with passively acquired antibody. It is not known if immunization of young infants with or without passive antibody would prime for measles specific cell mediated immune responses, or if immaturity of the infant immune system contributes to vaccine failure. Dr. Hayley Gans, along with Drs. Maldonado, DeHovitz and Arvin at Stanford Unversity Medical Center, evaluated and compared T cell and B cell responses to immunization with live attenuated measles or mump virus vaccine at 6, 9 or 12 months of age. Interestingly, vaccine specific T-cell priming occurred in each age group and was not inhibited by the presence of maternal antibody. These results indicated that measles immunization of young infants may be of benefit and efficacy of infant immunization deserves further study. These results were published in the Journal of Infectious Diseases. We have also provided support to Dr. Sulachni Chandwani in her evaluation of an early two-dose schedule for measles immunization of HIV infected children. This study demonstrated that HIV infected and uninfected children immunizaed at 6 and 12 months of age had measles antibody that persisted for at least one year after immunization. We are participating in a collaborative project initiated by Dr. Afzal, NIBSC to test tissue samples for the presence of measles virus genome to provie or disprove any relationship between measles immunization and subsequent diagnosis of inflammatory bowel disease. These studies will be completed within the next year.